Grok 5 Release Odds 2026: 57% by 31 December

This is a market page, not a rumour round-up, so here is the running order before you commit to it. Every price below was read from the Polymarket Gamma API at about 16:10 UTC on 19 September 2026 and quoted with its bid and ask, because on books this thin the midpoint on its own is misleading.

1. Grok 5 release odds across the three live date legs, with spreads and volumes.

2. Why the bigger book is on Grok 4.7 rather than Grok 5, and what that ladder says.

3. Musk's published target dates for 4.7 against what xAI actually shipped.

4. The Arena debut ladder, decomposed into a score distribution.

5. Why the 57% headline is not a price anyone can get filled at.

6. How each of these contracts resolves, and the resolution risks in the wording.

7. What would actually move these odds, and how to read them without getting burned.

Search for Grok 5 release odds and almost every page that comes back quotes the same stale figure, a 33% chance of shipping by 30 June 2026, from a market that expired months ago. Here is the ladder that is actually open, read this afternoon.

October 31: 10.0% mid, 9 bid against 11 ask, $2,977 of leg volume.

November 30: 16.0% mid, 14 bid against 18 ask, $1,210 of leg volume.

December 31: 57.0% mid, 40 bid against 74 ask, $4,474 of leg volume.

Two earlier legs, 15 August and 31 August, have already closed at zero. The whole event carries $13,739 of lifetime volume and $2,517 of book liquidity, and it runs until 04:59 UTC on 1 January 2027.

Read as a set, those three numbers describe a market that expects nothing soon and a scramble at the end of the year. The incremental probability of Grok 5 arriving in October is 10.0%. November adds only 6.0 points on top. December alone adds 41.0 points, which is more than the first two months combined by a factor of four.

That shape is not a forecast of steady progress towards a launch. It is what a market looks like when traders believe a release is being held for a moment rather than a milestone, and the end of the calendar year is the obvious moment. It also means the residual, the chance that Grok 5 does not appear at all in 2026, is 43.0% at the midpoint.

Hold that 43% next to the way this model has been discussed all year and the gap is the story. Grok 5 has been described as imminent since late 2025. The market that has to pay out on it gives better than four-in-ten odds that 2026 ends without it.

The single most useful thing to know about Grok 5 release odds is that the deeper market next to them is not about Grok 5 at all. A separate contract asks when the next Grok model at version 4.7 or higher reaches the public, and it carries $18,614 of volume against $13,739 for the entire Grok 5 ladder.

That market has 23 daily legs and ends on 30 September. Ten of them, every date up to and including 18 September, have already closed at zero. Thirteen are still live, and the one that matters most is the last: 'No release by September 30' at 17.65% mid, 2.3 bid against 33.0 ask.

Taken at the midpoint, that implies roughly an 82% chance a Grok 4.7 or higher lands inside the next eleven days. Taken at the ask, the honest reading is closer to 67%. Either way the market's central case is an incremental model within days, and a flagship generation months away or not at all.

The daily legs underneath are noisier. The 28 September leg shows the highest mid at 36.2%, but its quote is 0.1 bid against 72.3 ask, which is not a price so much as an empty book with a wide marker on either side. The 25 September leg reads 25.55% on a 2.2/48.9 spread, and 21 September reads 20.35% on 0.7/40.0.

The giveaway is that the thirteen open mids sum to 1.7065. In a properly priced set of mutually exclusive dates they would sum to about 1.00. Summing the asks instead gives 3.2430. Neither number is tradeable arithmetic. The midpoints are simply too far from executable prices on legs this thin, which is a caution worth carrying into every number on this page.

The reason a near-term release still prices below certainty is that xAI has missed this launch repeatedly and in public. The chronology below is assembled from trackers following Musk's posts on X, and it is worth laying out in full because it is the single best guide to how much a stated xAI date is worth.

24 July: Grok 4.7 'in 4 weeks', pointing at roughly 21 August.

28 July: 4.7 described as the 2.1-trillion-parameter model arriving a few weeks after 4.6.

12 August: Grok 4.6 ships. 4.7 'should be ready in 3 to 4 weeks', pointing at 2 to 9 September.

Start of September: 4.7 'comes out in 10 days'. Trackers date this post to 1 September and to 2 September, so the target it implies is either 11 or 12 September; the one-day disagreement does not change the outcome.

11 September: with the date passed, Musk says the model needs 'a few more days to cook'.

13 September: Musk names the successor, Grok 4.8, as a 2.5-trillion-parameter model trained on a new C++ software stack, while 4.7 remains unreleased.

14 September: Musk grades 4.7 himself as 'roughly on par with Opus 5.0, not 5.1. Better in some ways, worse in others.'

As of this afternoon, 19 September, there is still no Grok 4.7 model page, API identifier or price. For context on the cadence it is slipping against: Grok 4 landed on 9 July 2025, Grok 4.5 on 8 July 2026 and Grok 4.6 on 12 August 2026. Grok 4.6 scored 61 on the Artificial Analysis Intelligence Index with a 500,000-token context window at $2 per million input tokens.

Three announced windows have now come and gone. That record is the best available explanation for why the 30 September leg prices a residual of 17.65% instead of something closer to nothing.

The third Grok market is the most interesting and the least covered anywhere else. It asks what the next Grok 4.7+ will score on the Arena Text Arena overall leaderboard with style control off, measured at noon Eastern on the day after it first appears. It carries $11,390 of volume and $14,342 of liquidity, the deepest book of the three, and runs to 30 June 2027.

It is a cumulative ladder, so each leg asks for 'at least' a score: 1450+ at 51.5%, 1460+ at 29.5%, 1470+ at 15.5%, 1480+ at 10.5%, 1490+ at 8.3%, 1500+ at 8.05%. Spreads here are genuinely tight, a point or less on the first four legs, which makes this the one Grok book whose midpoints are worth taking at face value.

Subtract each rung from the one below it and you get the market's actual distribution for that debut score. Below 1450: 48.50%. 1450 to 1459: 22.00%. 1460 to 1469: 14.00%. 1470 to 1479: 5.00%. 1480 to 1489: 2.20%. 1490 to 1499: 0.25%. 1500 or above: 8.05%.

Now the benchmark that makes those numbers land. On the 13 September reading of that same board, SpaceXAI's best entry was grok-4.20-beta-0309-reasoning at 1451, with Anthropic top at 1508, Google at 1495, Alibaba at 1481 and OpenAI at 1471. So the 1450+ leg, at 51.5%, is very nearly a coin flip on whether the next Grok matches the score xAI is already posting.

Set that against Musk's own grading of 4.7 as Opus-5.0-class and the disagreement is stark. The man shipping it describes a frontier model. The book pricing it gives even odds that it fails to clear its predecessor's number, and only 8.05% that it reaches the 1500 mark where Anthropic sits.

One caveat on the tail. A 0.25% band for 1490-1499 sitting directly beneath 8.05% for 1500+ implies that clearing 1490 all but guarantees clearing 1500, which is not how score distributions behave. On a book this size that is more likely an artefact of traders clustering on the round 1500 strike than a considered view, and it is the one part of this ladder I would not build a position on.

Every page quoting Grok 5 release odds reports the midpoint and stops. The midpoint is the average of the best bid and the best offer, and on these books those two numbers can be a long way apart.

The December leg is the clearest case. It reads 57.0%, but the quote is 40 bid against 74 ask. If you want to buy the yes, you pay 74 cents for a dollar, not 57. If you want to sell it, you receive 40. The 57 is an arithmetic midpoint that exists on no screen anyone can hit.

That reframes the whole trade. The real question is not whether Grok 5 shipping in 2026 is worth more or less than 57 cents. It is whether it is worth more than 74 cents, on a model whose predecessor version has missed three target dates, and whose own successor has already been named while it sits unreleased. At 74 cents, the buyer needs a great deal to go right.

The October and November legs are much better behaved. October quotes 9 against 11 and November 14 against 18, spreads of two and four points. Those are prices you can actually work with, and they are the ones I would anchor on if I were forming a view on near-term timing.

The same discipline applies to the daily 4.7 ladder, where it matters even more. A 36.2% midpoint on a 0.1/72.3 quote carries close to zero information. When the spread is wider than the probability being quoted, the correct reading is that the market has no opinion on that leg, not that it has a strong one.

This is the habit worth taking away from the whole page: on any thin prediction market, read the ask before you read the headline. Our expected-value and Kelly calculators take an executable price rather than a mid for exactly this reason.

Resolution wording decides more of these contracts than anything that happens in a lab, and all three Grok markets carry specific risks in theirs.

The Grok 5 contract requires a product explicitly named Grok 5, or one clearly announced by xAI as the next flagship generation succeeding Grok 4. It states plainly that releases under the Grok 4 line, including 4.6 and 4.7, do not qualify, and neither do task-specialised or cost-efficiency variants unless xAI brands them as the next flagship. Access has to be public: an open beta or open waitlist counts, a closed beta does not.

The 4.7+ markets turn on version designation rather than branding. A qualifying model must carry 'Grok' in its name and be designated 4.7 or higher, with Grok 4.6 explicitly excluded, along with any rollout or snapshot of it. Separately numbered lines such as Grok Code Fast and Grok Imagine do not qualify, and nor do app or website version numbers that do not correspond to a new underlying model.

That wording spends an unusual amount of space on edge cases, which tells you the drafters expected them. xAI's naming has been irregular enough that the board's current top Grok entry is labelled grok-4.20-beta, and reasonable people can read a string like that as either below or above the 4.7 threshold. If you hold one of these legs, that ambiguity is a live risk rather than a theoretical one.

The debut market adds two more. It resolves on the score shown at noon Eastern on the calendar day after the model first appears, which is the noisiest possible reading of an Arena score, taken after roughly one day of votes rather than a settled sample. And a model marked AutoEval does not count as added at all, so an entry can appear on the leaderboard without starting the clock.

Every one of these also inherits the risk of its resolution source. These contracts settle on one external leaderboard, and a change to how that board publishes or labels its scores would land directly on the position.

Four things would reprice this cluster, in rough order of how quickly they would bite.

A Grok 4.7 release. This is the near-term event the market is waiting on, and it settles the 23-leg date ladder outright. It would also start the clock on the debut market, converting a distribution into a single number within about 48 hours.

A debut score. If 4.7 lands above 1470, the ladder's top rungs reprice hard and the case for Grok 5 being a genuine step up strengthens. If it lands below 1451, the market's near coin flip was right and xAI has shipped a model that does not beat its own board position, which would be the more consequential outcome for the 2026 Grok 5 legs.

A named Grok 5 date. xAI has given an explicit window for 4.7 three times now and missed it every time. A stated Grok 5 date would move the December leg immediately, though the track record above argues for discounting it heavily.

Grok 4.8. Musk named it on 13 September, before 4.7 shipped. If 4.8 gets a date while 4.7 is still pending, the reasonable reading is that the 4.x line continues into next year and Grok 5 slips out of 2026 entirely, which is the 43% residual becoming the base case.

Worth noting how small all of this is next to the surrounding market. The largest Grok contract on Polymarket right now is not about a model at all: 'Will Grok AI beat T1 in 2026?', on a League of Legends exhibition, carries $84,734 of monthly volume, more than four times the next Grok release market, and prices the AI at 1.95%.

If you take three things from this page, take these. The Grok 5 legs you can actually trade are October at 9/11 and November at 14/18; the December leg's 57% is a midpoint inside a 34-point spread and should be read as 74 cents if you are buying. The deeper book is on Grok 4.7, not Grok 5, and it expects an incremental model within days rather than a flagship this quarter. And the debut ladder, the one book here with tight spreads, is close to a coin flip on whether the next Grok beats the 1451 that xAI already posts.

The gap between those market prices and the public commentary is the whole opportunity, and also the whole warning. A model can be genuinely impressive and still settle a contract badly, because these contracts pay out on names, version strings, calendar dates and one leaderboard column rather than on capability.

Odsage tracks all five of these Grok markets on its release-odds pages and refreshes the prices through the day, and the calculators turn any quote here into expected value and Kelly sizing at an executable price rather than a mid. Prices in this article were read at about 16:10 UTC on 19 September 2026 and will have moved since.

Everything on this page is market data and context, not financial advice. Odsage is an information site and is not affiliated with Polymarket, xAI or Arena.